>>
> IIRC all distros have at least one component that's written in  
> Python. The Red
> Hat installer, Anaconda, is written in Python. I'm not sure about  
> Perl, though.
>
This is exactly the kind of reason why these are installed by  
default, I suspect. Much software that is part of the distro and is  
commonly used may need Perl and Python to run some install scripts.  
Certainly, any Apache install almost always is installed with Perl.  
Perl more than any other scripting language is pretty much bound to  
Linux and Unix by history and the loads of tools that use it/are  
built with it.